This invention relates to a structure and method of fabricating a resealable container with a magnetic closure system.
Containers store, retain and preserve numerous products. Containers are made from a variety of materials and are formed into many shapes and sizes. An exemplary conventional container is a cereal box made from paperboard. Generally, after placing a product in a container the container is closed. Containers designed for xe2x80x9cone timexe2x80x9d use generally do not have a re-closure system. However containers that dispense a product at intermittent intervals, such as cereal boxes, generally require a re-closure system. Conventional re-closure systems include an arrangement of opposing flaps on the container, for example at the top of a container. In a xe2x80x9ctab and slotxe2x80x9d system a tab extending from a first flap of the container is tucked into a slot located on an opposing flap. The tab and slot secure the opposing flaps in a closed position.
The aforementioned conventional container xe2x80x9ctab and slotxe2x80x9d re-closure system works well mechanically so long as the initial opening of the container does not tear or deform the container flaps or tab. The ease of initially opening the container depends upon the strength of the bonds that holds the opposing container flaps together. Conventionally, opposing flaps are secured to each other by various adhesive compounds. The type and amount of adhesive used is chosen to balance the strength of the container""s initial seal with the ease of initially separating the opposing flaps from each other. A major deficiency with the conventional xe2x80x9ctab and slotxe2x80x9d re-closure system is that after opening, the re-closure system does not provide an acceptable container barrier, especially for food or perishables items.
To address this shortcoming, perishable items are conventionally placed in a in an air, moisture, and vermin barrier, hereinafter referred to as xe2x80x9cmembrane.xe2x80x9d The membrane is vacuum sealed before the container is closed. For example, food products, such as cereal, crackers, biscuits, and cookies are conventionally sealed in a separate membrane before the container is initially sealed. The membrane serves to protect the product prior to the initial opening of the container and provides additional barrier protection after the container is open. Membrane materials typically comprise plastic, foil, or paper that has been laminated or coated to produce the desired barrier properties, such as air, moisture, and vermin control.
The integrity of the membrane and the available time interval for safely consuming the membrane""s product depends directly upon the care with which the membrane was initially opened as well as the care with which the membrane is re-closed after each opening. A typical membrane is re-closed by rolling the membrane from the top until the roll is tight against the product. Additional methods include clipping or otherwise securing the rolled up membrane to eliminate unrolling. A main disadvantage of the xe2x80x9crollingxe2x80x9d method is that it requires attention and care by the user. In addition, the rolling method often fails to produces an adequate seal for perishable products even when the user rolls according to best practice. In sum, conventional membrane re-closure techniques do not adequately protect perishable products. As a result the available consumption time for a product is not maximized.
A variety of other container re-closure systems exist. They can be classified into four general categories: (1) zippers, (2) pinching aids such as metallic ties and plastic clips, (3) spouts of various sorts including folding, pullout, and screw-top types, and (4) various closure flap retention systems. Zippers generally include a design where a container has an integrated zipper re-closure system formed in either the container or membrane. Pinching aids are conventional devices typically applied to the container flaps and/or membrane. An exemplary use of a pinching aid is to secure the rolled up portion of a membrane. Container spout designs include the use of paperboard or plastic elements secured to both containers and/or membranes that aid in removing the product from the container and can be repositioned to cover a container opening.
Flap retention systems secure moveable flaps to cover openings in the container. Conventionally flaps require the use of pressure sensitive adhesive or magnetic forces to secure the flap over the opening. An exemplary flap adhesive re-closure system is disclosed in U.S. Pat. No. 4,632,299 by Albert Holmberg, entitled xe2x80x9cReclosable Containers.xe2x80x9d It discloses a container with an opening and a closure flap to cover the opening. The flap""s perimeter has a pressure sensitive adhesive tape that secures the flap to the container. However, a major disadvantage of the Holmberg container is the possibility that debris will accumulate upon the adhesive coating causing incomplete sealing of the flap to the container. In addition, after repeated openings, the adhesive coating may weaken or fail, leaving the flap unsecured or partially unsecured to the container. In addition, the adhesive flap re-closure system requires care and attention by the user to properly secure the flap against the container.
An exemplary magnetic re-closure system is disclosed in U.S. Pat. No. 4,738,390 by Gerald Brennan, entitled xe2x80x9cMagnetic Closure Device For Envelope or the Like.xe2x80x9d A second exemplary magnetic re-closure system is disclosed in U.S. Pat. No. 3,749,301 by George Pecker, entitled xe2x80x9cMagnetically Sealable Container.xe2x80x9d Finally a third exemplary magnetic closure system is disclosed in U.S. Pat. No. 5,505,305 by Matthew Scholz, et. al., entitled xe2x80x9cMoisture-Proof Resealable Pouch and Container.xe2x80x9d The three examples each rely on magnetic attractive forces to secure a xe2x80x9cflap-likexe2x80x9d article to the container. However these conventional magnetic re-closure systems either fail to provide a secure container barrier for perishable items or require the use of a membrane in addition to the magnetic closure system to obtain acceptable product protection.
In summary, conventional container re-closure systems do not achieve an easy, low cost, and reliable re-closure system. As a result containers with conventional re-closure systems fail to provide an optimum air, moisture, and vermin barrier. In addition, adding a conventional membrane internal to the container to improve product protection results in increased packaging costs and fails to optimize product protection.
What is needed is a container with a re-closure system that provides an improved container seal after initial opening that is easy to open and close, is low cost, reliable, and requires little attention from the user. In addition, what is needed is a container with a re-closure system that eliminates the need and cost of an internal membrane.
The invention fulfills these needs not met by the prior art by providing a re-closure system for a container that is easy to open and close, reliable, and provides an air, moisture, and vermin barrier superior to that offered by a conventional membrane and container system.
In general, the invention includes a container body with at least one opening. A flap is partially secured to the container body and completely covers the container opening. The flap is secured to the container by a hinge or fold line and formed from the same substrate as the container body. The container body contains a first magnetic region adjacent to and surrounding the opening. The flap contains a second magnetic region aligned with and opposite the container body""s first magnetic region. The first and second magnetic regions are magnetically attracted to each other.
The contents of the container are removed by moving the flap to an open position. The container product is not placed in a membrane. The container is re-closed by returning the flap to a closed position. The flap is held in a closed position by magnetic attraction between the flap""s magnetic region and the container body""s magnetic region. The magnetic force is provided by forming active magnetic zones on both the container body and flap, or alternatively, one magnetic zone and a magnetically receptive zone arranged on the opposing part. The magnetic zones are dimensioned to extend around the entire border or perimeter of the opening and at optimized width to provide a good barrier seal.
In a first exemplary embodiment, magnetic gaskets cut from commercially available flexible magnetic sheet are secured to the container body and flap in the desired pattern and location. The magnetic gaskets are then polarized to create magnetically attractive regions.
In a second exemplary embodiment, magnetic regions are formed on the flap and container by printing ink containing ferrite material in the desired pattern and location. The ferrite regions are then polarized to create magnetically attractive regions.